It is one of the beauties of high-dollar, high-performance cars—and the companies that produce them—that even minimal changes are greeted with exceeding interest by the car-loving public. Case in point: Intelligently timed updates have kept us writing happily from the launch of the Vision SLR concept at the Detroit auto show in January 1999 and the series production market launch in May 2004 to this current iteration, an SLR Roadster with limited-series 722 treatment.

With the “722” designation, Mercedes is playing the Mille Miglia theme again. This was the starting number for the winning team of Stirling Moss and Denis Jenkinson at the 1955 Mille Miglia. Last year, Mercedes offered a more powerful, weight-optimized 722 Edition of the gullwing-door SLR coupe, limited to 150 units. A full 97 pounds lighter and 641hp strong, up from 617hp, it specifically appealed to collectors but also offered performance benefits.

The Roadster 722 S gets the same power-enhanced engine that was offered in last year's 722 Edition—a heavily modified variation of the supercharged 5.4-liter, three-valve V-8 that has been phased out in every other AMG model except for the Geländewagen. Torque is up from 575 lb-ft in the regular SLR to 605 lb-ft in the 722 S. All that power and force is channeled to the rear wheels through Mercedes-Benz’s own five-speed automatic transmission that can be manipulated with a switch to perform unusually quick shifts, thereby rivaling BMW's SMG box in harshness.

0 to 62 mph comes in a claimed 3.7 seconds, down 0.1 from the regular SLR roadster, and reported top speed is up 2 to 208 mph. The SLR has to be driven on its German home turf on a very low-traffic day to appreciate its autobahn qualities. The faster you go, the more comfortable the SLR feels. With its long and wide hood, the SLR is less rewarding on twisty country roads where it simply takes up too much pavement.

While we haven’t driven this specific version of the SLR yet, the considerably heavier roadster should feel nearly as stiff as the coupe on the road. Mercedes proudly points out that “thanks to favorable aeroacoustics, conversation during open-air journeys is still possible at well over 200kph (125 mph).” Your partner will be happy to know.

Despite its full carbon-fiber body, low weight is not a strong point of the SLR Roadster, which tips the scales at about 4000 pounds. Unlike the 722 Edition coupe, no weight-saving measures were taken with the Roadster 722 S, says a company spokesman. But it does have unique features, including a stiffer chassis lowered by 10 millimeters, specific 19-inch wheels, a "crystal antimony gray" paint job, semi-aniline leather/alcantara seats, red seat belts, embossed "722 S" lettering on the headrests and other details to set you apart from those commonplace SLRs littering your neighborhood.

When the SLR was first announced, Mercedes said total production would be limited to 3500 units altogether. But with just 1400 units sold by the end of last year, and a factory-confirmed halt of production at the end of 2009, this goal seems all but impossible to reach. We think Mercedes will have far less of a problem selling each of the 150 limited-edition SLR Roadster 722 S models. If European prices are an indication, the premium over the $497,750 SLR Roadster should be about $25,000. For this car, that's just another minimal change.